1. Field
The present disclosure relates to a multicarrier optical communication system, and in particular to an apparatus and method for detecting online failure and a system.
2. Description of the Related Art
A multicarrier communication system is a communication system based on multicarrier modulation, which is widely used in wireless communications and wired access networks due to its advantages of high transmission rate, high spectrum efficiency and anti-multipath and frequency domain fading. In a short-haul optical communication application, a multicarrier communication system, especially a discrete multi-tone (DMT) system based on intensity modulation and direct detection, gains much attention in the industry due to its simple structure and high transmission rate, and is deemed as one of leading technologies in a short-haul optical communication application scenario, such as a next-generation data center, etc. (refer to Document 1).
However, different from conventional wireless communication and a wired access network, on the one hand, a rate of a DMT optical communication system is greater than or equal to 100 Gb/s, and at such a high rate, influence of a change of a system distortion on the performance of the system will be enlarged; and on the other hand, a typical application scenario, such as a data center, has a higher requirement on stability of the DMT optical communication system, which often requires the system to be able to ensure operating consecutively at a stable rate. While in the known art, the DMT system tracks only changes of signal to noise ratios (SNRs) of the subcarriers, simply attributes a cause of the changes of the SNRs to changes of system noises and crosstalk, and attempts to ensure continuity of traffics in a subcarrier bit swap manner (refer to Document 2).
It can be seen that, the known art does not solve two key problems of the DMT optical communication system. First, localization of the cause of the changes of the SNRs. As the communication rate of the DMT optical communication system is very high, slight changes of various distortion in the system, such as a clock jitter, etc., will bring changes of the SNRs, while such degradation of the SNRs is not brought by noises or crosstalk, hence, the continuity of the traffics cannot be ensured by the subcarrier bit swap. Second, assurance of a stable transmission rate. As facing to terminal users, the conventional wireless communication and wired access network do not require the stability of the transmission rate, and hence, the known art deals with the changes of the SNRs based on adjusting the transmission rate. However, the DMT optical communication system is used in such scenarios as interconnection of large-scale servers in the data center, and requires that the transmission rate of the system is stable, such as satisfying specifications of a 100 Gb/s Ethernet, etc.
Document 1: “Discrete Multi-Tone for 100 Gb/s Optical Access Networks”, Takahara, T.; Fujitsu Labs. Ltd., Optical Fiber Communications Conference and Exhibition (OFC), 2014; and Document 2: “Adaptive Channel Tracking and Bit-Power Reallocation for 100 Gb/s Uncooled DMT Transceiver”, Bo Liu; Weizhen Yan; Lei Li; Hao Chen; Zhenning Tao; Takahara, T.; Rasmussen, J. C.; Drenski, T. Optical Communication (ECOC), 2014.
It should be noted that the above description of the background is merely provided for clear and complete explanation of the present disclosure and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of the present disclosure.